Pogba underwent a scan at Carrington the day after he was forced off in the first half against Basel with further tests using different imagery carried out last week.

United were hopeful the problem would heal without an operation, but sources have told ESPN FC that if there is no sign of progress, Pogba could have surgery in Finland in an attempt to speed up his recovery.

United play Southampton on Saturday before games against CSKA Moscow and Crystal Palace ahead of the international break.

After the two-week lay-off, United face four away games in a row against Liverpool, Benfica, Huddersfield and Swansea.

In the immediate aftermath of Pogba's injury, sources told ESPN FC United were fearful he would miss the trip to Anfield on Oct. 14 after initial scans revealed a muscle tear rather than just a strain.

Mourinho told a news conference on Friday: "Again, it is a great opportunity for other players to play. I am not going to cry or be counting the days for Paul to be back, not at all. Until then, I trust my people.

"Every injury is a different injury. I cannot tell you there is a rule about injured players. Not at all."